Thirty years after their “MarJo” fandom started, Marvin Agustin and Jolina Magdangal’s chemistry is still a palpable presence in their comeback romantic comedy series “Mommy Guard.” This time, though, Agustin is facing tough competition for Magdangal’s affection in award-winning actor Cedric Juan, who will also play her love interest in the series. READ: Marvin Agustin,